Monoacetyl-indoxyl and process of making same.



- NITED STATES PATENT OFFICE...

BERNHARD HEYMANN AND ALFRED HERRE, OF ELBERFELD, GERMANY, ASSIGNORS TO THE FARBENFABRIKEN OF ELBERFELD COMPANY, OF

NEW YORK, N. Y,

MONOACETYL-INDOXYL AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 657,539, dated September 11, 1900.

Application filed September 28, 1899. Serial No. 731,974. ($pecimens.)

has been described. We have now found that the acetylic group (I) which is bound to the oxygen atom can be split off much more easily by the action of saponifying agents than that acetylic group (II) which is bound to the nitrogen, and we have further succeeded in finding a saponifying process by means of which it is possible to split 0% the acetylic group (I) exclusively monoacetyl indoxyl of the probable formula coon,

OH. v to,

(which was unknown up to the present time) being produced. According to our researches this result is obtained by using such saponifying agents as are acting in a moderate manner--for instance, by employing sodium bisulfite, sodium sulfite, sodium phosphate, or the like agents acting in the same or in a similar manner.

In carrying out our new process practically we can proceed as follows, the parts being by l the shape of glittering needles.

weight: A mixture prepared from ten parts of carefully-pulverized diacetyl indoXyl and a solution of fifteen parts of sodium sulfite in two hundred parts of water is heated at about centigrade while being continuously stirred. By means of this operation the diacetyl indoxyl is by and by dissolved while the monoacetyl indoxyl begins to separate in When the precipitate thus obtained no longerincreases, the liquid is caused to cool the monoacetyl indoxyl, which is difficultly soluble in cold water, being nearly entirely separated in a pure state. It is finally filtered 0E, pressed, and dried. The new body thus obtained is a white crystalline powder and melts at 135 centigrade. It is easily soluble in boiling water, in alcohol, and in a cold diluted caustic soda-lye. On heating the caustic alkaline solution or on allowing the same to stand for a time the monoacetyl-indoxyl is entirely saponified, indoxyl being produced, which can be transformed in the usual manner into indigo. The monoacetyl indoxyl can therefore be employed for the production of indigo.

Having now described our invention and in what manner the same is to be performed, what we claim as new, and desire to secure by Letters Patent, is-

1. The process for the production of monoacetyl-indoxyl, which process consists in first heating diacetyl-indoxyl with a saponifying agent acting in a moderate manner, and secondly isolating the monoacetyl-indoxyl thus produced from the reaction mixture, substantially as hereinbefore described.

2. As a new article of manufacture the new monoacetyl-indoxyl having most probably the formula:

being when dry and pulverized a white crystailine powder melting at 135 Centigrade, names in the'preseneeof two subscribing wit easily soluble in boiling water, in alcohol and ne'sses. 5 v in"a cold dilute caustic s0da 1ye;yie1dii1gin-' BERNHARD HEYMANN.

. digo when heated with alkalies and 'snbsev ALFREDHERRE. 5 quently treated with atmospheric air, sub Witnesses:

stantially as hereinbefore described. j l R. E. JAHN,

In testimony whereof We have signed our OTTQ K6ifilq. M 

